This invention relates to an apparatus for determining an oxygen content and, more particularly, to an apparatus suitable for use in analyzing the oxygen contained as an impurity in a sealed container in which food or the like is packed.
Recently, food or the like having improved shelf-life are commercially produced, using gas-displacement packing technique, and are conveniently supplied for general consumers. A range of 0.015 to 5% of oxygen content may be acceptable as impurity in the sealed container in which commodities are packed by gas-displacement packing. In determining the oxygen content, predetermined amount of samples are generally taken from the random products by means of a syringe and the like and analyzed by a gas chromatography where the samples inevitably come into contact with ambient atmosphere after sampling and before introduction into measuring part of the chromatographic apparatus, resulting in erroneous determinations. Further, chromatographic method is very complicated to operate. Therefore, an apparatus which permits easy operation and precise determinations has still now been expected.
In this specification, the term "the apparatus" means the apparatus for determining oxygen content, "the borer" means the borer for boring a hole to take a gas sample from the sealed container, "the grasping lever" means the lever for grasping the container by hand, and "the water pool unit" means the unit comprising water pool for preventing atmospheric air from contacting with the products to be analyzed.
Now, it has been found that an oxygen content in a sealed container, in which commodities are packed by gas-displacement packing technique, can be easily and precisely determined by connecting a sampling tube such as a syringe with a measuring device in airtight manner, providing the sampling tube with a sampling zone in which a sample is introduced by a pumping means, connecting the sampling zone with either inlet or outlet path selectively through a change-over valve, providing the measuring device with a measuring zone therein, arranging an electrode for oxygen analysis in the measuring zone while connecting the measuring zone with the outlet path of the sampling tube in order to inject the sample to the electrode of the measuring zone via the outlet path by pumping the sample with the pumping means and by turning the change-over valve.